Under current practice in highway construction, twelve foot wide concrete lanes are poured in continuous lengths. Prior to pouring the concrete, forms are positioned to define the shape of the lane and metal reinforcement bars are placed within the forms. Reinforcement bars, or rebar, is placed on supports so that the rebar will be located at a depth of about the middle of the concrete. After the concrete has been poured and initially set, transverse cuts are made across the width of each lane at various intervals. The initial cut is about one inch wide and extends about one-half the depth of the concrete. The purpose of the cut is to weaken the concrete and cause the concrete to crack in the plane of the cut through the full depth of the concrete, thereby forming two abutting sections of highway. After the concrete is fully cured, the initial cut is then widened to about two inches, forming a groove. An expansion joint is then inserted in the groove. The expansion joint may be an extruded neoprene, pitch, or a semi-liquid material such as tar which is poured into the groove.
In multiple lane highways, additional lanes of highway are formed adjacent to the first lane. The additional lanes are formed in a manner similar to the first lane, however, the second lane is poured using the first lane as a longitudinal form. The lanes are formed without any coupling between the lanes so that each lane moves independent of the other lane. Shoulder lanes are formed adjacent to the outer lanes.
While the above described structure allows relatively minor elevation changes in the abutting sections of the highway, such structure does not readily accommodate expansion of the highway sections. While, the initial cut made in the highway creates two abutting sections of highway, the cut extends only one-half of the depth of the concrete, therefore the two sections cannot expand. Although the top half of one section of the highway is spaced away from another section, the lower half of each section remains fully against the other section. Therefore, each section may rise and fall relative to the other section but cannot expand without pushing against the other section. Any expansion of the highway sections causes the highway to buckle, or erupt, resulting in significant structural damage to the highway. Additionally, such method is labor intensive and time consuming. Particularly, each lane of the highway must be cut at least twice and the groove must be thoroughly cleaned to remove any foreign objects or materials before the expansion joint is inserted. In addition, as a result of cutting only one-half of the highway depth, it is possible that the highway will crack in a plane other than that of the cut resulting in substantial structural damage to the highway.
It would be desirable to provide a highway coupling apparatus which is easy to install that would couple sections of highway without requiring the cutting of the highway. It would further be desirable to provide such an apparatus that provides an expansion joint extending the fall depth of the highway. Additionally, it would be desirable to provide an apparatus which couples parallel highways sections while preventing separation of the highway sections.